05000271/LER-1990-008

LER 90-008-00:on 900529,identified That Cables Providing Power to post-accident Monitoring Instrument Loops Not Routed,Per Required Separation Criteria.Caused by Combination of Factors.Design Change prepared.W/900629 Ltr

ML20055D177
Person / Time
Site:	Vermont Yankee
Issue date:	06/29/1990
From:	Reid D VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-008, LER-90-8, VYV-90-219, NUDOCS 9007050083
Download: ML20055D177 (4)

LER-2090-008,

Event date:
Report date:
2712090008R00 - NRC Website

text

,

VERMONT YANKEE NUCLEAR POWER CORPORATION P. O, BOX 157 GOVERNOR HUNT ROAD VERNON, VERMONT 05354 June 29, 1990 VYV# 90-219 1

U.S. Nuclear. Regulatory. Commission Document Control' Desk' Washington, D.C. 20555

REFERENCE:

Operating O cense DPR-28 Docket No. 50-271 d Reportable Occurrence No. LER 90-08 'l

Dear Sirs:

- d I

As-defined by 100FR50,73,.we are reporting the attached. Reportable f Occurrence as LER 90-08. 3

.l j '

Very truly yours,-

VERMONT YANKEE NUCLEAR POWER CORPORATION  ;

1' Donald A. Reid Plant Manager-7 i

cc: Regional Administrator USNRC.

Region I 475 Allendale Road.

King of Prussia, PA 19406-k f-L-

! '9007050083 900629 PDR ~. ADOCK 05000:271

g. FDC 4 l

1

NRC Fora 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMS NO.3150-0104 (6-89) EXPIRES 4/30/92-

. ESTIMATED BURDEN PER RESPONSE TO COMPLY

. WITH THIS INFORMATION COLLECTION REQUEST:

• 50.0 HRS. FORWARD COMMENTS REGARDING LICENSEE EVENT REPORT (LER) BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P-530), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION

~

PROJECT (3160-0104), OFFICE OF MANAGEMENT

AND BUDGET, WASHINGTON, DC 20603.

FACILITY NAME ($) PAGE (8)

VERMONT YANKEE NUCLEAR POWER STATION DOCKET Ol5l010l0NO. (8)l 20l l7110F l1 l0l3

-TITLE (*) Failure to Meet Separation Criteria for Power Cables to Regulatory Guide 1.97

Instrumentation Loops EVENT DATE (5) LER NUMBER (*) REPORT DATE (7) OTHER FACILITIES INVOLVED (*)

MONTH DAY YEAR YEAR SEQ. # REV# MONTH DAY YEAR FACILITY NAMES DOCKET NO.(S) 0 5 0 0 0 0l5 2l9 9l0 9l0 -

0l0l8 -

0l0 0l6 2l9 9l0 0 5 0 0 0 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO RE0'MTS OF 10CFR 6: ( ONE OR MORE (ii)

MODE (*) N I20.402(b) __ 20.405(c) __ 50.73(a)(2)(iv) __ 73.71(b)

POWER 20.405(a)(1)(I) __ 50.36(c)(1) __ 50.73(a)(2)(v) __ 73.71(c) h LEVEL (10) _11 d 0__ 20.405(a)(1)(II) __ 50.36(c)(2) __ 50.73(a)(2)(vii) ._

OTHER:

B- ............... __ 20.405(a)(1)(III) _X 50.73(a)(2)(I) __ 50.73(a)(2)(viii)(A)

............... __ 20.405(a)(1)(iv) __ 50.73(a)(2)(II) __ 50.73(a)(2)(viii)(B)

............... 20.405(a)(1)(v) 50.7N.h)(2)(III) 50.73(a)(2)(x)

LICENSEE CONTACY FOR THIS LER (18)

NAME TELEPHONE NO.

AREA CODE DONALD A. REID, PLANT-MANAGER dd2 2ld7l-l7l7]Il1 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT ('8)

CAUSE SYST COMPNT MFR REPORTABLE ..... CAUSE SYST COMPNT MFR REPORTABLE ......

TO NPRDS ..... TO NPRDS ......

N/A l lll lll .. N/A l lll lll .

N/A l lll lll ..... N/A l lll lll ......

SUPPLEMENTAL REPORT EXPECTED (1*) EXPECTED M0 DA YR SUBMISSION lYES (If ves, complete EXPECTED SUBMISSION DATE) 'xl NO DATE (55) l l l ABSTRACT (Limit to 1400 spaces, i.e., approx. fifteen single-space typewritten lines) ('*)

On May 29, 1990, at approximately 1645 hours0.019 days <br />0.457 hours <br />0.00272 weeks <br />6.259225e-4 months <br />, with the reactor operating at 100% power, it was identified that four cables providing power to certain Post-Accident Monitoring 1 Instrument Loops (Regulatory Guide 1.97) were not routed in accordance with required separa-tion criteria. It was determined that the four cables are routed in cable trays used to

= carry the cables of the opposite division power cables.

ll Immediately following the identification of this event, a Justification for Continued Operation (JCO) was presented and accepted by the Plant Operations Review Committee (PORC).

=== Vermont Yankee made the determination that although the separation criteria was not fully met, all instrument loops were considered operational based upon their condition of being functional along with an evaluation of the deficiency relative to the design basis accident analysis. On May 30, 1990, the NRC appeared to disagree with the Vermont Yankee position.

This resulted in the four instrumentation loops being conservatively placed in a 30-day Limiting Condition for Operation (LCO).

This event was identified as a result of LER 89-09, in which Vermont Yankee committed to

- review and clarify the Plant Separation Criteria especially as it relates to instrumen-tation. The effort to revise the criteria is ongoing.

A temporary waiver of compliance to the Technical Specifications has been requested and granted. A design change is being prepared to provide separation for the power cables that supply the Regulatory Guide 1.97 instruments, this design change will be installed during the 1990 refuelina outage.

NRC Form 366 (6-89)

NRC F;rm'366A U.S, NUCLEAR REGULATORY COMMISSION APPROVED OMS NO.3150-0104 (6-89)l U PIRES 4/30/92

'J -

ESTIMATED BURDEN PER RESPONSE TO COMPLY

, WITH THIS INFORMATION COLLECTION REQUEST:

" f o 50.0 HRS. FORWARD COMMENTS REGARDING i LICENSEE EVENT REPORT (LER) BURDEN ESTIMATE TO THE RECORDS AND REPORTS E TEXT CONTINUATION MANAGEMENT BRANCH (P-530), U.S. NUCLEAR m REGULATORY COMMISSION, WASHINGTON, DC ja 20555, AND TO THE PAPERWORK REDUCTION ,

' PROJECT (3160-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20603.

UTILITY;NAME ( ) DOCKET NO. (a) LER NUMBER (*) PAGE (*)

5 YEAR SEO. # REV#

VERMONT YANKEE NUCLEAR POWER STATION 0l Sl 0l 0l 0l 2l,]

71 9l0 -

0l0l8 -

0l0 0l2 0F Ol3 TEXT (If more space is required, use additional NRC Form 366A) (17)

-DESCRIPTION OF EVENT On May 29, 1990, at approximately 1645 hours0.019 days <br />0.457 hours <br />0.00272 weeks <br />6.259225e-4 months <br />, with the reactor operating at 100% power,

.it.was identified that four cables providing power to certain Post-Accident Monitoring L . Instrument Loops (Regulatory Guide 1.97) were not routed in accordance with required separa-L? tien cri_teria. It was determined that the four cables are routed in cable trays used to-

carry the cables of the opposite division power cables. The equipment affected is one of th3 two divisions required to provide Post-Accident Monitoring Instrumentation for the following parameters

• Drywell Atmospheric Temperature

• Torus Water Temperature

• Torus Air. Temperature

• Torus Air Pressure Immediately following identification of this condition, a Justification for continued Operation (JCO) was presented and accepted by the Plant Operations Review Committee (PO'lC).

V3rmont Yankee.made the determination that although the separation criteria was not fully met, all instrument loops were considered operational based upon their condition of being functional along with an evaluation of the deficiency relative to the design basis accident en21ysis. On May 30, 1990, the NRC appeared to disagree with the Vermont Yankee position.

This resulted in the four instrumentation loops being conservatively placed in the 30-day.

Liaiting Condition for Operation (LCO) as required by Technical Specification Table 3.2.6.

CAUSE OF EVENT The root cause of this event has been determined to be a combination of several factors, j As determined by LER 89-09, requirements for separation of analog instrumentation are 1 . unclear in the Vermont Yankee Separation Criteria. The original plant design considered i; ranalog instrumentation to be non-essential (NNS) with the Vital and Instrument AC buses b draigned to provide reliable sources of power. Although the Vital and Instrument AC buses f themselves are powered from redundant sources, thel distribution circuits fed from them may not be considered redundant since these power cables were non-designated cables to NNS instrumentation and routed accordingly.

% .During the implementation of RG 1.97 design, existing (original) equipment was used where porsible to provide the indicating and/or recording function of required RG 1.97 parameters.

1 =As a result, existing power supplies to the Control Room Panels from the Vital and

' ' Instrument AC buses were used, however, a verification of cable routing of these power supplies was not performed to ensure redundancy in accordance with RG 1.97 requirements M b;cause of the belief that the Vital and Instrument AC buses provided the required cable siparation since they were powered from redundant sources.

NRC Form 366A (6-89) lI

NRC.FtrQ 366A -U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMS NO.3150-0104 (6-89) ', .

EXPIRES 4/30/92 vo- . . ESTIMATED BURDEN PER RESPONSE TO COMPLY

/ [" ' ;

WITH THIS INFORMATION COLLECTION REQUEST:

+' 50.0 HRS. FORWARD COMMENTS REGARDING c

2 <

' LICENSEE. EVENT REPORT (LER) BURDEN ESTIMATE TO THE RECORDS-AND REPORTS TEXT-CONTINUATION MANAGEMENT-BRANCH (P-530), U.S. NUCLEAR.

REGULATORY COMMISSION, WASHINGTON, DC -

20555, AND TO THE PAPERWORK REDUCTION PROJECT-(3160-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON.-DC 20603.

UTILITY NAME (1) DOCKET NO. (*) LER NUMBER (*) PAGE (8)

YEAR SEQ. # REV#

VERMONT YANKEE NUCLEAR POWER STATION d d d d d 217l 1 9l0 -

0l0l8 -

0l0 d3 0F d3 TEXT (If more space is required, use additional NRC Form 366A) (1')

ANALYSIG OF EVENT

.The events detailed in this report do not have adverse safety implications to public

.hselth or safety.

~The subject instrument loops are completely functional. Redundancy and separation of squipment and cable is satisfied for the majority of each instrument loop installation.

~This includes all potentially harsh environment areas and missile producing areas. It is only:the relatively short length of power cable routed in non-harsh environment where caparation. requirements are not sa'.isfied (from the one Control Room panel to the Cable V: ult and back into another Control Room panel). In addition, the subject cable trays are eafety class and located-in the Cable Vault which is protected by a fire detection and euppression system.

The instrument loops involved perform a monitoring function only. .There is no automatic

' function initiated by this equipment. Therefore, no automatic safety feature is jeopardized by the loss of any of these loops.

CORRECTIVE' ACTIONS This event'was identified as a result of the Corrective Actions associated with LER 89-09, in'which Vermont Yankee committed to review and clarify the Plant Separation Criteria. The effortito enchance the criteria is ongoing, and will specifically address separation require-ments for redundant equipment powered from the Instrument and Vital AC buses.

A temporary waiver of compliance from Technical Specifications-Table 3.2.6, 30-day LCO Rtquirements hes been requested and granted.

.A design change is being prepared to provide the required separation for the power cabling'to the Regulatory Guide 1.97 instruments. This design change will be installed prior to the start-up from the 1990 refueling outage.

o

ADDITIONAL INFORMATION A similar event was reported to the Commission in LER 89-09.

NRC Form 366A (6-89)

. . .